Kolmašová I, Santolík O, Manninen J
Department of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czechia.
Faculty of Mathematics and Physics, Charles University, Prague, Czechia.
Nat Commun. 2024 Aug 21;15(1):7166. doi: 10.1038/s41467-024-51684-0.
Lightning generated electromagnetic impulses propagating in the magnetospheric plasma disperse into whistlers - several seconds long radio wave signals with decreasing frequency. Sometimes, multiple reflections form long echo trains containing many whistlers with increasing dispersion. On January 3, 2017, two necessary prerequisites - a pronounced lightning activity and a magnetospheric plasma duct - allowed for observations of a large number of whistler echo trains by the high-latitude station in Kannuslehto, Finland. Our investigation reveals that the duct existed for nearly eight hours. We show that causative lightning sferics arrived to the duct entry from three different winter thunderstorms: a small storm at the Norwegian coast, which produced energetic lightning capable to trigger echo trains in 50% of cases, and two large storms at unexpectedly distant locations in the Mediterranean region. Our results show that intense thunderstorms can repetitively feed electromagnetic energy into a magnetospheric duct and form whistler echo trains after subionospheric propagation over distances as large as 4000 km.
闪电产生的电磁脉冲在磁层等离子体中传播时会分散成啸声——持续数秒的频率递减的无线电波信号。有时，多次反射会形成包含许多具有递增色散的啸声的长回波序列。2017年1月3日，两个必要前提条件——明显的闪电活动和磁层等离子体管道——使得芬兰坎努斯莱赫托的高纬度观测站能够观测到大量啸声回波序列。我们的研究表明，该管道存在了近八个小时。我们发现，引发闪电的天电从三场不同的冬季雷暴到达管道入口：一场在挪威海岸的小风暴，其产生的高能闪电在50%的情况下能够触发回波序列；还有两场位于地中海地区出人意料的遥远位置的大风暴。我们的结果表明，强烈雷暴能够反复将电磁能量注入磁层管道，并在经亚电离层传播长达4000千米的距离后形成啸声回波序列。
